http://hdl.handle.net/2117/219 Sun, 19 May 2013 23:48:05 GMT 2013-05-19T23:48:05Z webmaster.bupc@upc.edu Universitat Politècnica de Catalunya. Servei de Biblioteques i Documentació no http://hdl.handle.net/2117/19033 Title: A new approach to the internal sizing of paper via biotechnological processes Authors: García Ubasart, Jordi; Roncero Vivero, María Blanca; Vidal Lluciá, Teresa Abstract: This work deals with the study of a new biotechnological procedure, employing laccase in combination with hydrophobic compounds, for the biomodification of fibres and the internal sizing of paper. Cellulose fibres from eucalyptus kraft pulp, unbleached and TCF bleached, were incubated with laccase, in combination with a series of hydrophobes. Laccase treatments of cellulose fibres with lauryl gallate conferred the lowest level of water penetration in handsheets. It was observed that the hydrophobization of paper was not possible using the hidrophobe alone. The coupling of lauryl gallate onto cellulose fibres was firstly denoted by kappa number analysis, and further demonstrated by IR spectroscopy. The internal sizing of paper proved to be effective regardless the lignin content of eucalyptus fibres Mon, 29 Apr 2013 12:35:29 GMT http://hdl.handle.net/2117/19033 2013-04-29T12:35:29Z García Ubasart, Jordi; Roncero Vivero, María Blanca; Vidal Lluciá, Teresa no This work deals with the study of a new biotechnological procedure, employing laccase in combination with hydrophobic compounds, for the biomodification of fibres and the internal sizing of paper. Cellulose fibres from eucalyptus kraft pulp, unbleached and TCF bleached, were incubated with laccase, in combination with a series of hydrophobes. Laccase treatments of cellulose fibres with lauryl gallate conferred the lowest level of water penetration in handsheets. It was observed that the hydrophobization of paper was not possible using the hidrophobe alone. The coupling of lauryl gallate onto cellulose fibres was firstly denoted by kappa number analysis, and further demonstrated by IR spectroscopy. The internal sizing of paper proved to be effective regardless the lignin content of eucalyptus fibres http://hdl.handle.net/2117/18998 Title: Effect of the laccase mediator system on the fibre properties of TCF bleached kraft pulp Authors: Cadena Chamorro, Edith Marleny; Cusola Aumedes, Oriol; Vidal Lluciá, Teresa; Torres López, Antonio Luis Abstract: The application of the laccase mediator system (L stage) to TCF bleached pulp from Eucalyptus globulus with a low residual lignin content provides useful information about its effect in the hexenuronic acids content, functional groups (carboxyl and carbonyl) and electrokinetic properties as ζ potential and surface charge. The use of laccase from Trametes villosa in combination with the mediator 1- hydroxybenzotriazole (HBT) produces an oxidation of the cellulose to carbonyl groups, and reduced the amount of carboxyl groups present in TCF pulp through partial removal of hexenuronic acids from it. This result can open up new prospects for increasing brightness stability. Additionally, the laccase mediator system modifies the surface charge and ζ potential of the fibre suspension for the removal de ionizables groups in TCF pulp. The reduction of the carboxyl content additionally alters the charge on fibre surfaces; this may be useful with a view to reducing pulp processing costs since a decreased content in ionizable groups can be expected to reduce consumption of cationic additives used in the production of paper. As regards electrokinetic properties, the laccase mediator system reduces the ζ potential of fibre suspensions by acting on carboxylic and hexenuronic acids. The biomodification of the chemical composition of TCF pulp by the laccase mediator system causes no substantial changes in the properties of the refined pulp (ºSR, %WRV); this indicates that the L treatment does not affect development of the primary effects of refining, and also that it may have a side effect on the fibre-water system by decreasing the proportion of ionizable groups and altering the electrokinetic properties of the pulp Fri, 26 Apr 2013 09:16:28 GMT http://hdl.handle.net/2117/18998 2013-04-26T09:16:28Z Cadena Chamorro, Edith Marleny; Cusola Aumedes, Oriol; Vidal Lluciá, Teresa; Torres López, Antonio Luis no The application of the laccase mediator system (L stage) to TCF bleached pulp from Eucalyptus globulus with a low residual lignin content provides useful information about its effect in the hexenuronic acids content, functional groups (carboxyl and carbonyl) and electrokinetic properties as ζ potential and surface charge. The use of laccase from Trametes villosa in combination with the mediator 1- hydroxybenzotriazole (HBT) produces an oxidation of the cellulose to carbonyl groups, and reduced the amount of carboxyl groups present in TCF pulp through partial removal of hexenuronic acids from it. This result can open up new prospects for increasing brightness stability. Additionally, the laccase mediator system modifies the surface charge and ζ potential of the fibre suspension for the removal de ionizables groups in TCF pulp. The reduction of the carboxyl content additionally alters the charge on fibre surfaces; this may be useful with a view to reducing pulp processing costs since a decreased content in ionizable groups can be expected to reduce consumption of cationic additives used in the production of paper. As regards electrokinetic properties, the laccase mediator system reduces the ζ potential of fibre suspensions by acting on carboxylic and hexenuronic acids. The biomodification of the chemical composition of TCF pulp by the laccase mediator system causes no substantial changes in the properties of the refined pulp (ºSR, %WRV); this indicates that the L treatment does not affect development of the primary effects of refining, and also that it may have a side effect on the fibre-water system by decreasing the proportion of ionizable groups and altering the electrokinetic properties of the pulp http://hdl.handle.net/2117/18887 Title: Cyclodextrin functionalization of several cellulosic substrates for prolonged release of antibacterial agents Authors: Cusola Aumedes, Oriol; Tabary, Nicolas; Naceur Belgacem, Mohamed; Bras, Julien Abstract: Several cellulosic substrates have been surface-functionalized with cyclomaltoheptaose (b-cyclodextrin, b-CD) using citric acid as a crosslinker agent to obtain new surface-modified materials able to release antiseptic molecules over a prolonged period, in view of their use in medical domain. Three different commercial cellulosic substrates were used, namely: (i) an uncoated paper, (ii) a crepe paper, and (iii) a medical bandage. They were successfully grafted by a crosslinked polymer consisting on b-CD molecules as assessed by scanning electron microscopy and Fourier transform infrared spectroscopy analysis. Several time–temperature kinetic cycles were performed to reach the optimum curing parameters. The grafted and nongrafted samples were loaded with chlorhexidine digluconate (digCHX), a widely used antiseptic agent. The drug-delivery kinetics of the encapsulated digCHX was carried out by immersing the sample under investigation into an aqueous medium, and the quantity of the released digCHX was measured, as a function of time, by UV spectroscopy. The optimal grafting conditions were established on the basis of the highest weight gain. These samples did not give the best release performance. Nevertheless, several grafted substrates were able to uptake an appreciable amount of active molecules and release them over a prolonged time of about 20 days Fri, 19 Apr 2013 11:04:05 GMT http://hdl.handle.net/2117/18887 2013-04-19T11:04:05Z Cusola Aumedes, Oriol; Tabary, Nicolas; Naceur Belgacem, Mohamed; Bras, Julien no Several cellulosic substrates have been surface-functionalized with cyclomaltoheptaose (b-cyclodextrin, b-CD) using citric acid as a crosslinker agent to obtain new surface-modified materials able to release antiseptic molecules over a prolonged period, in view of their use in medical domain. Three different commercial cellulosic substrates were used, namely: (i) an uncoated paper, (ii) a crepe paper, and (iii) a medical bandage. They were successfully grafted by a crosslinked polymer consisting on b-CD molecules as assessed by scanning electron microscopy and Fourier transform infrared spectroscopy analysis. Several time–temperature kinetic cycles were performed to reach the optimum curing parameters. The grafted and nongrafted samples were loaded with chlorhexidine digluconate (digCHX), a widely used antiseptic agent. The drug-delivery kinetics of the encapsulated digCHX was carried out by immersing the sample under investigation into an aqueous medium, and the quantity of the released digCHX was measured, as a function of time, by UV spectroscopy. The optimal grafting conditions were established on the basis of the highest weight gain. These samples did not give the best release performance. Nevertheless, several grafted substrates were able to uptake an appreciable amount of active molecules and release them over a prolonged time of about 20 days http://hdl.handle.net/2117/18297 Title: Application of surface enzyme treatments using laccase and a hydrophobic compound to paper-based media Authors: Cusola Aumedes, Oriol; Valls Vidal, Cristina; Vidal Lluciá, Teresa; Roncero Vivero, María Blanca Abstract: A new approach for the hydrophobization of finished cellulosic substrates based on a previously reported enzymatic technique is proposed. Commercial finished paper was hydrophobized by using laccase from Trametes villosa in combination with lauryl gallate (LG) as hydrophobic compound. The efficiency of the method was increased by the use of a lignosulfonate as a natural dispersant to improve the surface distribution of LG on the paper, raise its hydrophobicity and help preserve the enzyme activity. No similar threefold effect from a single compound for the improvement of enzymatic treatments was previously reported. The influence of processing conditions including the LG dose, treatment time and temperature was also examined, resulting in further increased hydrophobicity. Efficient fiber bonding and chemical functionalization were confirmed by thorough washing and Soxhlet extraction of the paper. As shown here for the first time, enzyme treatments have the potential to improve the surface hydrophobicity of paper-based media Thu, 14 Mar 2013 11:44:20 GMT http://hdl.handle.net/2117/18297 2013-03-14T11:44:20Z Cusola Aumedes, Oriol; Valls Vidal, Cristina; Vidal Lluciá, Teresa; Roncero Vivero, María Blanca no A new approach for the hydrophobization of finished cellulosic substrates based on a previously reported enzymatic technique is proposed. Commercial finished paper was hydrophobized by using laccase from Trametes villosa in combination with lauryl gallate (LG) as hydrophobic compound. The efficiency of the method was increased by the use of a lignosulfonate as a natural dispersant to improve the surface distribution of LG on the paper, raise its hydrophobicity and help preserve the enzyme activity. No similar threefold effect from a single compound for the improvement of enzymatic treatments was previously reported. The influence of processing conditions including the LG dose, treatment time and temperature was also examined, resulting in further increased hydrophobicity. Efficient fiber bonding and chemical functionalization were confirmed by thorough washing and Soxhlet extraction of the paper. As shown here for the first time, enzyme treatments have the potential to improve the surface hydrophobicity of paper-based media http://hdl.handle.net/2117/18230 Title: Laccase from Pycnoporus cinnabarinus and phenolic compounds: can the efficiency of an enzyme mediator for delignifying kenaf pulp be predicted? Authors: Andreu Terrén, Glòria; Vidal Lluciá, Teresa Abstract: In this work, kenaf pulp was delignified by using laccase in combination with various redox mediators and the efficiency of the different laccase–mediator systems assessed in terms of the changes in pulp properties after bleaching. The oxidative ability of the individual mediators used (acetosyringone, syringaldehyde, p-coumaric acid, vanillin and actovanillone) and the laccase–mediator systems was determined by monitoring the oxidation–reduction potential (ORP) during process. The results confirmed the production of phenoxy radicals of variable reactivity and stressed the significant role of lignin structure in the enzymatic process. Although changes in ORP were correlated with the oxidative ability of the mediators, pulp properties as determined after the bleaching stage were also influenced by condensation and grafting reactions. As shown here, ORP measurements provide a first estimation of the delignification efficiency of a laccase–mediator system. Tue, 12 Mar 2013 16:04:36 GMT http://hdl.handle.net/2117/18230 2013-03-12T16:04:36Z Andreu Terrén, Glòria; Vidal Lluciá, Teresa no Kenaf, Laccase, Phenolic mediators, Oxidation–reduction potential In this work, kenaf pulp was delignified by using laccase in combination with various redox mediators and the efficiency of the different laccase–mediator systems assessed in terms of the changes in pulp properties after bleaching. The oxidative ability of the individual mediators used (acetosyringone, syringaldehyde, p-coumaric acid, vanillin and actovanillone) and the laccase–mediator systems was determined by monitoring the oxidation–reduction potential (ORP) during process. The results confirmed the production of phenoxy radicals of variable reactivity and stressed the significant role of lignin structure in the enzymatic process. Although changes in ORP were correlated with the oxidative ability of the mediators, pulp properties as determined after the bleaching stage were also influenced by condensation and grafting reactions. As shown here, ORP measurements provide a first estimation of the delignification efficiency of a laccase–mediator system. http://hdl.handle.net/2117/18145 Title: Enzymatic grafting of natural phenols to flax fibres: development of antimicrobial properties Authors: Fillat Latorre, Amanda; Gallardo Román, Óscar; Vidal Lluciá, Teresa; Pastor Blasco, Francisco I. Javier; Díaz Lucea, Pilar; Roncero Vivero, María Blanca Abstract: Unbleached flax fibres for paper production were treated with laccase from Pycnoporus cinnabarinus and low molecular weight phenols (syringaldehyde – SA, acetosyringone – AS and p-coumaric acid – PCA) to evaluate the potential of this treatment to biomodify high cellulose content fibres. After the enzymatic treatment with the phenols, an increase in kappa number was found, probably due to a covalent binding of the phenoxy radicals on fibres. Grafting was more evident in pulps treated with PCA (an increase of 4 kappa number points with respect to the laccase control was achieved). Paper handsheets from treated pulps showed antimicrobial activity against the bacteria tested: Staphylococcus aureus, Pseudomonas aeruginosa and Klebsiella pneumoniae. An important reduction on microbial count was obtained after incubation of liquid cultures of the bacteria with grafted handsheets. AS and PCA grafted fibres showed a high antibacterial activity on K. pneumoniae, getting a nearly total growth inhibition. AS fibres also caused a high reduction in bacterial population of P. aeruginosa (97% reduction). Optical properties of handsheets from treated pulps were also determined, showing a brightness decrease and increase in coloration, evaluated by CIE L*a*b* system, caused by the laccase induced grafting of the phenols. The results suggest that these low molecular weight phenols, covalently bound to the flax fibres by the laccase treatment, can act as antimicrobial agents and produce handsheets with antimicrobial activity Fri, 08 Mar 2013 11:09:37 GMT http://hdl.handle.net/2117/18145 2013-03-08T11:09:37Z Fillat Latorre, Amanda; Gallardo Román, Óscar; Vidal Lluciá, Teresa; Pastor Blasco, Francisco I. Javier; Díaz Lucea, Pilar; Roncero Vivero, María Blanca no Unbleached flax fibres for paper production were treated with laccase from Pycnoporus cinnabarinus and low molecular weight phenols (syringaldehyde – SA, acetosyringone – AS and p-coumaric acid – PCA) to evaluate the potential of this treatment to biomodify high cellulose content fibres. After the enzymatic treatment with the phenols, an increase in kappa number was found, probably due to a covalent binding of the phenoxy radicals on fibres. Grafting was more evident in pulps treated with PCA (an increase of 4 kappa number points with respect to the laccase control was achieved). Paper handsheets from treated pulps showed antimicrobial activity against the bacteria tested: Staphylococcus aureus, Pseudomonas aeruginosa and Klebsiella pneumoniae. An important reduction on microbial count was obtained after incubation of liquid cultures of the bacteria with grafted handsheets. AS and PCA grafted fibres showed a high antibacterial activity on K. pneumoniae, getting a nearly total growth inhibition. AS fibres also caused a high reduction in bacterial population of P. aeruginosa (97% reduction). Optical properties of handsheets from treated pulps were also determined, showing a brightness decrease and increase in coloration, evaluated by CIE L*a*b* system, caused by the laccase induced grafting of the phenols. The results suggest that these low molecular weight phenols, covalently bound to the flax fibres by the laccase treatment, can act as antimicrobial agents and produce handsheets with antimicrobial activity http://hdl.handle.net/2117/17932 Title: Use of cyclic voltammetry as an effective tool for selecting effcient enhancers for oxidative bioprocesses: importance of pH Authors: Aracri, Elisabetta; Tzanov, Tzanko; Vidal Lluciá, Teresa Abstract: Seven natural phenols and two synthetic compounds were evaluated by means of cyclic voltammetry as enhancers for the oxidation of the lignin model compound veratryl alcohol (VAl) and a sulfonated lignin (SL). Their electrochemical behaviors and catalytic efficiencies (CEs) against both substrates were assessed as a function of pH. A general increase in CE of the phenols was for the first time observed in the oxidation of VAl at pH 7 and 8. Methyl syringate (MS), syringic acid (SRC), and syringaldehyde (SRD) exhibited the highest CEs against VAl among the studied phenolic compounds despite the reduced stabilities of their phenoxy radicals. This was a result of favorable stability−reactivity balances, which were apparently influenced by both the chemical structures of the enhancers and the experimental conditions. Violuric acid (VAc) proved the most efficient compound in oxidizing lignin, followed by SRD and MS, which showed regeneration in the interval of pHs studied Fri, 22 Feb 2013 11:50:22 GMT http://hdl.handle.net/2117/17932 2013-02-22T11:50:22Z Aracri, Elisabetta; Tzanov, Tzanko; Vidal Lluciá, Teresa no Seven natural phenols and two synthetic compounds were evaluated by means of cyclic voltammetry as enhancers for the oxidation of the lignin model compound veratryl alcohol (VAl) and a sulfonated lignin (SL). Their electrochemical behaviors and catalytic efficiencies (CEs) against both substrates were assessed as a function of pH. A general increase in CE of the phenols was for the first time observed in the oxidation of VAl at pH 7 and 8. Methyl syringate (MS), syringic acid (SRC), and syringaldehyde (SRD) exhibited the highest CEs against VAl among the studied phenolic compounds despite the reduced stabilities of their phenoxy radicals. This was a result of favorable stability−reactivity balances, which were apparently influenced by both the chemical structures of the enhancers and the experimental conditions. Violuric acid (VAc) proved the most efficient compound in oxidizing lignin, followed by SRD and MS, which showed regeneration in the interval of pHs studied http://hdl.handle.net/2117/17489 Title: Bleached dissolving pulps applying laccase treatments Authors: Quintana, Elisabet; Valls Vidal, Cristina; Roncero Vivero, María Blanca Abstract: A biobleaching sequence, using a laccase enzyme (Trametes Villosa) in combination with different mediators, was applied to softwood dissolving cellulose in order to study its bleaching efficiency and its potential in terms of kappa number, ISO brightness and viscosity. The tested mediators were classified as synthetic compounds such as HBT (1-hydroxybenzotriazole) and VA (violuric acid), and as natural compounds such as SA (syringaldehyde) and pCA (p-coumaric acid). The influence of the enzymatic stage in the bleaching sequence was compared with a control treatment and also with a conventional alkaline hydrogen peroxide stage. The contribution of L (laccasemediator) stage on the effluent properties is important for evaluating and minimizing its environmental impact. Therefore, effluent properties (COD, colour, residual enzyme activity and toxicity) were determined. Laccase-VA system showed the most promising results in reducing kappa number and increasing brightness without detriment to viscosity Wed, 23 Jan 2013 10:51:06 GMT http://hdl.handle.net/2117/17489 2013-01-23T10:51:06Z Quintana, Elisabet; Valls Vidal, Cristina; Roncero Vivero, María Blanca no A biobleaching sequence, using a laccase enzyme (Trametes Villosa) in combination with different mediators, was applied to softwood dissolving cellulose in order to study its bleaching efficiency and its potential in terms of kappa number, ISO brightness and viscosity. The tested mediators were classified as synthetic compounds such as HBT (1-hydroxybenzotriazole) and VA (violuric acid), and as natural compounds such as SA (syringaldehyde) and pCA (p-coumaric acid). The influence of the enzymatic stage in the bleaching sequence was compared with a control treatment and also with a conventional alkaline hydrogen peroxide stage. The contribution of L (laccasemediator) stage on the effluent properties is important for evaluating and minimizing its environmental impact. Therefore, effluent properties (COD, colour, residual enzyme activity and toxicity) were determined. Laccase-VA system showed the most promising results in reducing kappa number and increasing brightness without detriment to viscosity http://hdl.handle.net/2117/17435 Title: Performance of new and commercial xylanases for ECF and TCF bleaching of eucalyptus kraft pulp Authors: Valls Vidal, Cristina; Gallardo Román, Óscar; Vidal Lluciá, Teresa; Pastor Blasco, Francisco I. Javier; Díaz Lucea, Pilar; Roncero Vivero, María Blanca Abstract: Since xylanases can differ widely in their bleaching efficiency, the performance of one new and two commercial xylanases was evaluated in an eucalyptus kraft pulp following XD (X: xylanase; D: chlorine dioxide) and XP (P: hydrogen peroxide) sequences. The new xylanase did not show a significant bleach boosting effect but increased the hexenuronic acid (HexA) removal by 10% after the D stage. The two commercial xylanases behaved in a different way, being one of them (XC) the most effective in increasing delignification (9%) and brightness (3%ISO). Its effectiveness was related to its greater action on releasing the xylan polymer, thus producing also a strong decrease in the HexA contents during the enzymatic stage (15%). All xylanases produced morphological changes in the fibre surfaces, but only with XC cracks and holes that improved the diffusion of reactives were observed. Finally, the best bleaching results were obtained with the XD sequence and therefore, a complete bleaching sequence XDEopD1 (Eop: alkaline extraction with oxygen and peroxide) was carried out with the best enzyme Mon, 21 Jan 2013 12:01:00 GMT http://hdl.handle.net/2117/17435 2013-01-21T12:01:00Z Valls Vidal, Cristina; Gallardo Román, Óscar; Vidal Lluciá, Teresa; Pastor Blasco, Francisco I. Javier; Díaz Lucea, Pilar; Roncero Vivero, María Blanca no Since xylanases can differ widely in their bleaching efficiency, the performance of one new and two commercial xylanases was evaluated in an eucalyptus kraft pulp following XD (X: xylanase; D: chlorine dioxide) and XP (P: hydrogen peroxide) sequences. The new xylanase did not show a significant bleach boosting effect but increased the hexenuronic acid (HexA) removal by 10% after the D stage. The two commercial xylanases behaved in a different way, being one of them (XC) the most effective in increasing delignification (9%) and brightness (3%ISO). Its effectiveness was related to its greater action on releasing the xylan polymer, thus producing also a strong decrease in the HexA contents during the enzymatic stage (15%). All xylanases produced morphological changes in the fibre surfaces, but only with XC cracks and holes that improved the diffusion of reactives were observed. Finally, the best bleaching results were obtained with the XD sequence and therefore, a complete bleaching sequence XDEopD1 (Eop: alkaline extraction with oxygen and peroxide) was carried out with the best enzyme http://hdl.handle.net/2117/17384 Title: Simulation of bleaching of soda pulp from Hesperaloe funifera by polynomial and neural fuzzy models Authors: Rosal, Antonio; Valls Vidal, Cristina; Roncero Vivero, María Blanca; Rodríguez Pascual, Alejandro Abstract: Influence of variables [soda, (0.5 to 3.0%), hydrogen peroxide (1.0 to 10.0%) and time (1 to 5 h)] in the bleaching of soda pulp of Hesperaloe funifera, on the properties of bleached pulps, was studied. Polynomial and neural fuzzy models had reproduced the results of Kappa number, brightness and viscosity of the pulps with errors less than 10 and 15%, respectively. By simulating the bleaching process of pulp H. funifera, with the polynomial and neural fuzzy models, the optimal values of operating variables can be found, so that the properties of bleached pulps differ little from their best values and instead will save chemical reagents, energy and plant size, operating with lower values of operating variables. Thus, by application of polynomial models, it was found that operating with a soda concentration of 0.5%, a hydrogen peroxide concentration of 5.5% and for a processing time of 3 h, it was possible to get a pulp with a brightness of 65.9% and a viscosity of 587 ml/g. Wed, 16 Jan 2013 10:48:32 GMT http://hdl.handle.net/2117/17384 2013-01-16T10:48:32Z Rosal, Antonio; Valls Vidal, Cristina; Roncero Vivero, María Blanca; Rodríguez Pascual, Alejandro no Influence of variables [soda, (0.5 to 3.0%), hydrogen peroxide (1.0 to 10.0%) and time (1 to 5 h)] in the bleaching of soda pulp of Hesperaloe funifera, on the properties of bleached pulps, was studied. Polynomial and neural fuzzy models had reproduced the results of Kappa number, brightness and viscosity of the pulps with errors less than 10 and 15%, respectively. By simulating the bleaching process of pulp H. funifera, with the polynomial and neural fuzzy models, the optimal values of operating variables can be found, so that the properties of bleached pulps differ little from their best values and instead will save chemical reagents, energy and plant size, operating with lower values of operating variables. Thus, by application of polynomial models, it was found that operating with a soda concentration of 0.5%, a hydrogen peroxide concentration of 5.5% and for a processing time of 3 h, it was possible to get a pulp with a brightness of 65.9% and a viscosity of 587 ml/g. http://hdl.handle.net/2117/17382 Title: Influence of enzyme and chemical adsorption on the thermal degradation path for eucalyptus pulp Authors: Barneto, A. G.; Valls Vidal, Cristina; Ariza, José; Roncero Vivero, María Blanca Abstract: Changes in thermal degradation path of eucalyptus pulp support enzymes (laccase from Trametes villosa) and chemicals (Tris–HCl or tartrate–tartaric buffer) adsorption on cellulose during biobleaching, thereby increasing cellulose amount that degrades at low temperature and decreasing the apparent crystallinity (ApC) of cellulose crystallites. Changes in ApC, which can be assessed by thermogravimetric analysis—but not X-ray diffraction spectroscopy—affect cellulose volatilization; thus, the higher ApC is, the lower is char production and the higher the volatilization temperature. A linear relationship between ApC and the volatilization/charring ratio (V/C) was observed in this work Wed, 16 Jan 2013 10:24:33 GMT http://hdl.handle.net/2117/17382 2013-01-16T10:24:33Z Barneto, A. G.; Valls Vidal, Cristina; Ariza, José; Roncero Vivero, María Blanca no Changes in thermal degradation path of eucalyptus pulp support enzymes (laccase from Trametes villosa) and chemicals (Tris–HCl or tartrate–tartaric buffer) adsorption on cellulose during biobleaching, thereby increasing cellulose amount that degrades at low temperature and decreasing the apparent crystallinity (ApC) of cellulose crystallites. Changes in ApC, which can be assessed by thermogravimetric analysis—but not X-ray diffraction spectroscopy—affect cellulose volatilization; thus, the higher ApC is, the lower is char production and the higher the volatilization temperature. A linear relationship between ApC and the volatilization/charring ratio (V/C) was observed in this work http://hdl.handle.net/2117/17381 Title: Obtaining biobleached eucalyptus cellulose fibres by using various enzyme combinations Authors: Valls Vidal, Cristina; Cadena Chamorro, Edith Marleny; Roncero Vivero, María Blanca Abstract: Various combinations of laccases, xylanase and cellulase were used to biobleach cellulose fibres from eucalyptus. The Trametes villosa and Myceliophthora thermophila laccases were used in combination with violuric acid (VATvL system) and methyl syringate (MeSMtL system), respectively, as mediator. A dissimilar mode of action of the two systems was found: the VATvL treatment released both hexenuronic acids and lignin, whereas the MeSMtL released lignin alone. Pulp properties were further improved by applying the mediator before the enzyme during treatment. Pulp properties comparable to those provided by industrial TCF sequences were obtained by inserting a xylanase pretreatment before VATvL, but no significant effect was observed after the cellulase pretreatment. As an added value, the resulting enzymatically bleached fibres possess a reduced hexenuronic acid content. The chemical oxygen demand of the effluents from each stage was also assessed Wed, 16 Jan 2013 08:53:18 GMT http://hdl.handle.net/2117/17381 2013-01-16T08:53:18Z Valls Vidal, Cristina; Cadena Chamorro, Edith Marleny; Roncero Vivero, María Blanca no Various combinations of laccases, xylanase and cellulase were used to biobleach cellulose fibres from eucalyptus. The Trametes villosa and Myceliophthora thermophila laccases were used in combination with violuric acid (VATvL system) and methyl syringate (MeSMtL system), respectively, as mediator. A dissimilar mode of action of the two systems was found: the VATvL treatment released both hexenuronic acids and lignin, whereas the MeSMtL released lignin alone. Pulp properties were further improved by applying the mediator before the enzyme during treatment. Pulp properties comparable to those provided by industrial TCF sequences were obtained by inserting a xylanase pretreatment before VATvL, but no significant effect was observed after the cellulase pretreatment. As an added value, the resulting enzymatically bleached fibres possess a reduced hexenuronic acid content. The chemical oxygen demand of the effluents from each stage was also assessed http://hdl.handle.net/2117/17380 Title: A neural fuzzy model applied to hydrogen peroxide bleaching of non-wood soda pulps Authors: Rosal, Antonio; Valls Vidal, Cristina; Ferrer, Ana; Rodríguez, Alejandro Abstract: A neural fuzzy model was used to examine the influence of pulp bleaching variables of empty fruit bunches from oil palm (EFB) and Hesperaloe funifera, such as soda concentration (0.5-3%), hydrogen peroxide concentration (1-10%) and processing time (1-3 h), on Kappa number, brightness and viscosity. The experimental results are reproduced with errors below 10% and 15% for EFB and H. funifera, respectively. Bleaching pulp simulation permits to obtain optimal values of the operating variables, so that the properties of bleached pulps will only slightly differ from their best values, while the lower values of the operating variables will save chemical reagents, energy and plant size. Thus, if applying 0.5% soda and 3% peroxide for 3 h, it is possible to get a pulp with a brightness of 74.9% and a viscosity of 716 mL/g, for EFB pulp, and of 63.3% and 584 mL/g, respectively, for H. funifera pulp Wed, 16 Jan 2013 08:29:38 GMT http://hdl.handle.net/2117/17380 2013-01-16T08:29:38Z Rosal, Antonio; Valls Vidal, Cristina; Ferrer, Ana; Rodríguez, Alejandro no A neural fuzzy model was used to examine the influence of pulp bleaching variables of empty fruit bunches from oil palm (EFB) and Hesperaloe funifera, such as soda concentration (0.5-3%), hydrogen peroxide concentration (1-10%) and processing time (1-3 h), on Kappa number, brightness and viscosity. The experimental results are reproduced with errors below 10% and 15% for EFB and H. funifera, respectively. Bleaching pulp simulation permits to obtain optimal values of the operating variables, so that the properties of bleached pulps will only slightly differ from their best values, while the lower values of the operating variables will save chemical reagents, energy and plant size. Thus, if applying 0.5% soda and 3% peroxide for 3 h, it is possible to get a pulp with a brightness of 74.9% and a viscosity of 716 mL/g, for EFB pulp, and of 63.3% and 584 mL/g, respectively, for H. funifera pulp http://hdl.handle.net/2117/17345 Title: Laccase-TEMPO oxidation of sisal pulp for improving paper strength properties: influence of the operating conditions Authors: Aracri, Elisabetta; Valls Vidal, Cristina; Vidal Lluciá, Teresa Abstract: The oxidation of a low lignin content sisal pulp by laccase-TEMPO system has been investigated and evaluated as potential approach for improving the paper strength properties. TEMPO mediated oxidation was found to cause the formation of aldehyde and carboxyl groups in proportions dependent on the particular reaction conditons. The treatment was performed in acetate buffer pH 5 at room temperature and the influence of process variables (viz laccase dose, TEMPO dose and reaction time)on the properties of the pulp and the resulting handsheets was assessed by using a three-variable sequential statistical plan. The increase of aldehyde groups was found to be closely aligned with enhanced wet strength which was ascribed to the formation of inter-fibre convalent bonding through hemiacetal linkages Mon, 14 Jan 2013 14:38:05 GMT http://hdl.handle.net/2117/17345 2013-01-14T14:38:05Z Aracri, Elisabetta; Valls Vidal, Cristina; Vidal Lluciá, Teresa no The oxidation of a low lignin content sisal pulp by laccase-TEMPO system has been investigated and evaluated as potential approach for improving the paper strength properties. TEMPO mediated oxidation was found to cause the formation of aldehyde and carboxyl groups in proportions dependent on the particular reaction conditons. The treatment was performed in acetate buffer pH 5 at room temperature and the influence of process variables (viz laccase dose, TEMPO dose and reaction time)on the properties of the pulp and the resulting handsheets was assessed by using a three-variable sequential statistical plan. The increase of aldehyde groups was found to be closely aligned with enhanced wet strength which was ascribed to the formation of inter-fibre convalent bonding through hemiacetal linkages http://hdl.handle.net/2117/16480 Title: Nanofibrillated cellulose as reinforcement for high performance cement mortar composites Authors: Ardanuy Raso, Mònica; Claramunt Blanes, Josep; Parés Sabatés, Ferran; Aracri, Elisabetta; Vidal Lluciá, Teresa Abstract: In this work, the preparation and characterization of new cement mortars reinforced with nanofibrillated cellulose fibres has been carried out. The effect of the fibre fibrillation degree on the mechanical performance of the obtained composites is presented and analyzed, taking into account the reinforcement final size depending on the intensity of the mechanical treatment applied. On the one hand, conventional pulps have been obtained by subjecting sisal fibres to a soft mechanical treatment and, on the other hand, nanofibrillated cellulose pulps have been prepared by the application of a high intensity refining process. These pulps were incorporated and homogenously dispersed in cement mortars, and subsequently, the resulting pastes were cured for 28 days. The mechanical performance of the different composites was determined by flexure tests Thu, 13 Sep 2012 09:11:54 GMT http://hdl.handle.net/2117/16480 2012-09-13T09:11:54Z Ardanuy Raso, Mònica; Claramunt Blanes, Josep; Parés Sabatés, Ferran; Aracri, Elisabetta; Vidal Lluciá, Teresa no In this work, the preparation and characterization of new cement mortars reinforced with nanofibrillated cellulose fibres has been carried out. The effect of the fibre fibrillation degree on the mechanical performance of the obtained composites is presented and analyzed, taking into account the reinforcement final size depending on the intensity of the mechanical treatment applied. On the one hand, conventional pulps have been obtained by subjecting sisal fibres to a soft mechanical treatment and, on the other hand, nanofibrillated cellulose pulps have been prepared by the application of a high intensity refining process. These pulps were incorporated and homogenously dispersed in cement mortars, and subsequently, the resulting pastes were cured for 28 days. The mechanical performance of the different composites was determined by flexure tests